Adjustments in a Morley PFV pedal

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...

Adjustments in a Morley PFV pedal

Postby saransk » 13 Dec 2019, 21:36

the Morley PFV (Phaser/Volume) pedal is remarkably like the classic Univibe with an optical control of the LFO.
the schematic shows the design is very much like a "double univibe"
There are 5 controls on the circuit board not found on any other optical (lamp/photoresitor) circuit I've seen.
1 - appears at the output of the LFO - goes through the Phase travel Control - and then the lamp driver.
2 - is labled Lamp Bias and "fine tunes" the lamp driver bias after it goes through the Center Control (turning this trimmer made the lamp brighter)
3 - the third on is in between two other photoresistors that probaly have to do with the manual phase control
4 - the forth seems to be the "fine tuning" for the Harmonic Emphasis control - "Feedback"
5 - the 5th is a Mixer - dry to wet

I can't find anything about how to best set these controls, as I mentioned they aren't found in most phase shifters
I set the bias, #3, like I would for a Univibe - not too bright
I set the mixer, #5, about 2/3 to wet signal.
I have no idea how to figure out the others. Not helped that the only schematic is not really clear in it's printing.

Anyone who might understand the lamp driver circuit better - your ideas for the trimmers would be greatly apreciated. - see schematic
The pedal is working - the LFO is a bit fast but it has a really great phase shifter effect.

Thanks
Michael
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